Low HIV-1 transmitted drug resistance in Bulgaria against a background of high clade diversity

Ivailo Alexiev, Anupama Shankar, A. M. J. Wensing, Danail Beshkov, Ivaylo Elenkov, Mariyana Stoycheva, Daniela Nikolova, Maria Nikolova, William M. Switzer

Research output: Contribution to journalArticleAcademicpeer-review


To determine transmitted drug resistance (TDR) and HIV-1 genetic diversity in Bulgaria.
The prevalence of TDR and HIV-1 subtypes was determined in 305/1446 (21.1%) persons newly diagnosed with HIV/AIDS from 1988 to 2011. TDR mutations (TDRMs) in protease and reverse transcriptase were defined using the WHO HIV drug mutation list. Phylogenetic analysis was used to infer polymerase (pol) genotype.
TDRMs were found in 16/305 (5.2%) persons, 11 (3.6%) with resistance to NRTIs, 5 (1.6%) with resistance to NNRTIs and 3 (0.9%) with resistance to PIs. Dual-class TDRMs were found in three (1.0%) patients and one statistically supported cluster of TDRMs comprising two individuals with subtype B infection. TDRMs were found in 10 heterosexuals, 4 MSM and two intravenous drug users. Phylogenetic analyses identified high HIV-1 diversity consisting of mostly subtype B (44.6%), subtype C (3.3%), sub-subtype A1 (2.6%), sub-subtype F1 (2.3%), sub-subtype A-like (3.6%), subtype G (0.3%), CRF14_BG (1.6%), CRF05_DF (1.3%), CRF03_AB (0.3%) and unique recombinant forms (1.3%).
We found a low prevalence of TDR against a background of high HIV-1 genetic diversity among antiretroviral-naive patients in Bulgaria. Our results provide baseline data on TDR and support continued surveillance of high-risk populations in Bulgaria to better target treatment and prevention efforts.
Original languageEnglish
Pages (from-to)1874-1880
Number of pages7
JournalJournal of Antimicrobial Chemotherapy
Issue number6
Publication statusPublished - Jun 2015


  • antiretroviral mutations
  • surveillance
  • viral heterogeneity
  • eastern Europe


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